Program computer for elevator system



April 25, 1967 J. R. DINNING 3,315,765

PROGRAM COMPUTER FOR ELEVATOR SYSTEM oo @p-aor 7 INVENTOR. JOHN R.DINNING ATTORNEY April 25, 1967 J. R. DINNING 3,315,765

PROGRAM COMPUTER FOR ELEVATOR SYSTEM INVENTOR. JOHN R. DINNING BY ,9RNEYS ATT April 25, 1967 J. R. DINNING 3,315,765

PROGRAM COMPUTER FOR ELEVATOR SYSTEM Filed Jan. 20, 1959 5 Sheets-Sheet5 JOHN R. DINNING ATTORNEYS United States Patent 3,315,765 PROGRAMCOMPUTER FOR ELEVATOR SYSTEM John R. Dinning, Los Angeles, Calif.,assignor to Toledo This invention relates to automatic elevator systemsand in particular to trafiic sensing or measuring equipment that iseffective to alter the program of operation of the elevator system inaccordance with the trafiic demands as such demands occur.

It is customary to provide groups of automatic elevators withsupervisory control equipment to correlate the operation of the severalcars and thus improve the service rendered by the system of elevators.The supervisory control, for example, is ordinarily arranged to controlthe dispatching of the elevator cars from the terminal landings of thesystem, to control the starting of idle cars, and vary the generalprogram of operation in accordance with the demand for service and thenumber of cars in operation.

In the ordinary automatic elevator installation a supervisory control isarranged to afford several types or programs of operation designed tomeet different trafiic patterns. These different patterns of operationmay either be set up by a clock mechanism in anticipation of theparticular traffic demands or a supervisor or starter may observe thetraflic and select the programs accordingly.

The principal object of this invention is to provide traffic sensingmeans for automatically selecting an appropriate program of operationand putting such program into operation.

-' Another object of the invention is to provide traffic sensingmechanism that is responsive to the number of down hall callsregistered, the loading of the cars during their upward and downwardtravel, and the number of stops made by each car in the course ofoperation and that correlates these factors to select an appropriatepro- 1 gram of operation.

A still further object of the invention is to provide trailic measuringmeans arranged to provide a quantitative measurement of the traflicdemand.

A still further object of the invention is to provide tratfic measuringequipment in the form of a bridge circuit in which the resistance of onearm of the bridge is varied according to the trafiic being sensed, andthe resistance of a second arm of the bridge is varied to balance thebridge and indicate the trafiic level. The bridge is thus, in effect, aself-balancing arrangement such that the bridge detector need not besensitive to levels of excitation but need only be sensitive to thedirection of the unbalance and initiate corresponding corrections untilthe unbalance is removed.

More specific objects and advantages are apparent from the followingdescription of a preferred form of the invention.

According to the invention a traflic counting relay system is energizedto either add or subtract trafiic indicating units according to thetraflic level then indicated by the relay system and the actual trafiicdemand of the elevator system. The measured traffic levels, as indicatedby the bridge circuit, are employed to select corresponding appropriatemodes of operation of the elevator system.

A preferred form of the invention is illustrated in the accompanyingdrawings.

In the drawings:

FIG. I is a schematic illustration of a plurality of elevator carsarranged to serve a plurality of floors.

FIG. II is a fragmentary schematic diagram of a hall call registeringcircuit.

FIG. III is a schematic diagram of bridge circuits arranged to beresponsive to demands for service.

FIG. IV is a schematic diagram of part of the operating mechanism forthe trafiic demand counting mechanism and means for including stops madeby each of the cars as part of the traflic count.

FIG. V is a schematic diagram of the relay counting system for countingand indicating the traffic demand as sensed by the bridge circuits shownin FIG. III.

FIG. V1 is a schematic diagram of a plurality of timing circuitsarranged to be responsive to the traific measuring equipment forselecting appropriate operating patterns of the elevator system inaccordance with such trafiic measurements.

These specific figures and the accompanying description are intendedmerely to illustrate the invention and not to impose limitations on itsscope.

In an elevator system constructed according to the invention a pluralityof cars 10a, 10b, 10c and 10d are suspended by cables 11 that run oversheaves or .pulleys 12 mounted on armature shafts 13 of hoisting motors14. The cables 11 after passing over the pulleys 12 are connected tocounterweights 15 that balance the dead weight of the cars 10 and aportion of the full passenger load therein. Each drive motor 14 isconnected through leads 16 to a direct current generator 17 which inturn is driven by an alternating current motor 18. The motor 18 isnormally energized directly from a three-phase power line whenever thecar is to be placed in readiness for operation.

A floor selector machine 19, one for each car, is driven preferablythrough drive and synchronizing means connected to the armature shaft 13and is arranged to switch control circuits in accordance with the travelof its car 10 up and down its path of travel. The floor selectormachines may, alternatively, be driven 'by tapes or cables connecteddirectly to the cars. Each floor selector machine 19 is connectedthrough an electrical control cable 20 to a supervisory control panel 21that may be energized through supply leads 22. The supervisory controlpanel 21 is also connected through signal cable 23 to a series of pushbuttons 24 for down calls and 25 for up calls, the push buttons beinglocated at the various floors served by the elevator system.

The control circuits for operating the elevator system include a largenumber of relays and associated circuits a few of which are illustratedin the accompanying drawings. The contacts of relays are given the samereference numeral as the operating coils or the relays as a whole andare identified by line numbers in the accompanying drawings. Thus, inthe code strip to the right of each figure, in line with each of therelay coils and after its reference character, is an indication of thenumber and location of contacts operated by such coil. The contacts arelisted according to the lines in which they are located and those thatare normally closed are identified by underscoring the line number.

The relay coils and/ or contacts operated by such coils are listed forready reference. These are:

B-Brake relay CC--No car call relay DL-Down memory relay DO-Door limitrelay HB--Hall button relay HCR-High call reverse relay IS-In servicerelay 82D, 83D, etc-Down hall call relays SlU, S2U, etc-Up hall callrelays ULUp memory relay W-l, W-2, W-3Load weighing relays lF-First orlobby floor relay 3 430No hall call relay 471One car in service473--Three cars in service 474-Four cars in service 531Up add detectorrelay 531R-Up add detector reset coil 531XUp add auxiliary relay532--Down add detector 532RDown add detector reset coil 532XDown addauxiliary 533Up subtract detector 533RUp subtract detector reset coil533XUp subtract auxiliary relay 534--Down subtract detector 534RDownsubtract detector reset coil 534X--Down subtract auxiliary relay 535A-535G -Up traffic counting relays 536A -536G Down traffic countingrelays 560-Light trafiic relay 581Up peak timer 582--Down peak timer583--Up peak cancel timer 584-Down peak cancel timer These relays areconventional except for the detector relays 531, 532, 533 and 534 whichhave a plurality of coils connected in series, as illustrated in lines309 to 311 or 323 to 327, to secure the best sensitivity and havingreset coils appearing at lines 502 and 505. These detector relayspreferably have magnetic contacts or magnetic latch characteristics toinsure reliable operation of the contacts under weak current and thusrequire reset coils to separate the contacts as soon as a circuitresponds to their closure. The up and down trafiic counting relays 535Athrough G and 536A through G are composite relays having a ratchetsection for alternately operating certain of the contacts and havingother contacts operated directly by the pawl mechanism of the relay sothat they operate each time the operating coil is energized. Thecontacts that operate each time the coil is energized are indicated by aprime following the reference numeral, while those that are operated onalternate releases of the energizing power are indicated without anyspecial reference.

Referring to FIG. II, a hall call may be registered by pressing the hallcall button 24 or 25 at a landing and thereby closing the circuits tothe associated relays. Thus, for example, if an intending passenger atthe top floor presses the top floor button 24 he closes contacts S12D inline 202 so that current may flow from an energized control circuitsupply line CS through a coil HB of a hall button relay, the contacts ofpush button 24, lead 26. and an operating coil 812D of the twelfth floordown hall call relay, to the return lead 00. The down hall call relayS12D is thereupon energized and closes its contacts S12D, line 203, tocomplete a by-pass circuit around the push button 24 and thus maintainthe operating coil of the relay energized. A circuit is also completedat this time through lead 27 to the appropriate contacts of the floorselector machines so that a car may answer such call. When the call isanswered a circuit is completed through a neutralizing coil of the hallcall relay 812D and lead 28 to deenergize the relay. Similar circuitsare provided for each of the other floors. For intermediate floors, twosuch relays are provided, one for up calls and one for down calls.

FIGURE III A bridge circuit for measuring the trafiic demand in the downdirection is illustrated in lines 301 to 312 inclusive. This bridgecircuit includes a first or balancing arm comprised of parallelresistors R1 to R7 that are introduced into the circuit according to thenumber of traffic counting relays 536A through G that are in their on 1Composite relays having armature actuated contacts and ratchet operatedcontacts.

condition. A second arm of the bridge comprises resistors RX, one foreach down hall call relay, that are introduced into the bridge circuitas long as the corresponding down hall call relays are energized. Thebridge also comprises ratio arm resistors R8 and R9 shown in lines 301and 312. Preferably the resistors R8 and R9 are equal to each other andeach is approximately onefifth of one of the resistors RX or R1 throughR7. The unbalance in the bridge circuit is detected by a pair ofpolarized relays 532 and 534. These relays are connected across thediagonal of the bridge through normally closed contacts 536A through5366 which, as explained later, momentarily open the detector circuit asa change in the count in the counting relays is made following eachdetection of an unbalance. The down add detector relay 532 is polarizedto be responsive to current flowing from the second arm of the bridge,the hall call resistors RX, through the coil of the relay, the normallyclosed chain of contacts 536A through G and resistor R8. The downsubtract detector relays 534 are polarized to respond to current flowingin the opposite direction. 7

The parallel combination of the hall call resistors RX is shunted byressitors RY representing load in the down traveling cars as long as thecircuits in lines 313 to 319 inclusive are completed. These circuits forthe first car are illustrated in lines 313 to 316 and similar circuitsfor the other cars are indicated in lines 317, 318 and 319. Theresistors RY, each equal in value to a resistor RX, are arranged to beinserted in shunt with the resistors RX whenever the car is in serviceas indicated by closure of contacts ISa, the car is loaded to a certaindegree as in:- dicated by closure of contacts W-l for a 20% load, WZ fora 40% load and W-3 for a 60% load, the car is not at the first orterminal floor as indicated by closure of contacts lFa in line 313, andis conditioned for down travel as indicated by closure of down memorycontacts DLa shown in line 313.

In the operation of this circuit, assuming that it is orig inallybalanced, the addition or registration of a hall call by adding aresistor RX into the second arm of the bridge results in current flowupwardly through the down add detector relays 532. This relay thereuponcloses its contacts and, by means of the circuits shown in FIGS. IV andV, results in the operation of a counting relay which momentarily opensthe detector arm of the bridge circuit by opening one of the countingrelay contacts and adds another one of the resistors R1 through R7 intothe first arm of the bridge. If the addition of the resistors R1 throughR7 results in a balancing of the bridge no further action takes place.However, if it is not suflicient to balance the bridge, current againflows through the detector relay 532 to initiate another step. in thecounting chain thus adding another resistor to the first arm of thebridge. Likewise, if one or two or more of the hall calls are an sweredso that the corresponding resistors RX are cut out of the bridge arm,current flows downwardly through the detector arm of the bridge, throughthe coils of the down subtract relay 534 thus initiating a subtractaction to return one of the counting relays to its off condition therebyremoving one of the resistors R1 through R7 from the bridge circuit.This action may be repeated if necessary to secure a balance in thebridge.

The circiuts indicated in lines 317 to 319 correspond, for cars B, C andD, to the circiuts shown in lines 313 and 316 for car A and act on thedown trafiic bridge in the same manner.

An up trafiic measuring bridge is illustrated in lines 320, to 328 andincludes some of the circuits shown in lines 313 to 319. This bridgeincludes a first or balancing arm that includes resistors R13 to R19that are connected in parallel with each other into the bridge armaccording to the number of up trafiic counting relays 535A through Gthat may then be actuated. The ratio arms for this bridge are providedby resistors R12, line 320, and R20, line 328. A second or measuring armof the bridge comprises resistors RY and RZ for the various cars thatare arranged to be added in to the second or measuring arm as long asthe car is conditioned for service as indicated by closure of its inservice contacts ISa, is loaded as indicated by closure of contact W-1for a 20% load, W2 for a 40% load or W-3 for a 60% load, is not at thefirst floor, and is conditioned for upward travel as indicated byclosure of up memory contacts UL, line 315. Additionally, theregistration of a car call adds resistor RZ in parallel with resistorsRY as a measure of the traflic being served by car A. Similar circuitsfor cars B, C and D are indicated in lines 317 to 319. These resistorsmake up the principal portion of the second or measuring arm of the uptraflic bridge. In addition resistor R11 and under certain conditions Rare included in shunt with these as long as there is an up callregistered at the lobby floor as indicated by closure of contacts SIU inline 320. The resistor R10 is shunted around resistor R11 as long as theone car in service relay contacts 471 are closed to indicate a heaviertrafiic demand and thus accelerate the starting of additional cars. Upadd detector relay 531 and up subtract detector relay 533 are similar inconstruction to the down add and down subtract relays 532 and 534 andare sensitive polarized relays equipped with magnetic contacts ormagnetic latches to provide reliable contact operation. These relayshave reset coils 531R and 533R shown in line 502 for resetting detectorrelays as an additional counting relay is added or subtracted from thecounting relay chain.

FIGURE IV When the up add detector relay 531 operates in response to anincreased up traffic demand it closes its contacts 531, line 408, tocomplete a circuit from the energized control circuit lead CS through anoperating coil 531X of an up add auxiliary relay 531X. Similarly, whenthe down a-dd detector relay 532 operates in response to an increase indown traific demand it closes its contacts 532 in line 421 to energize adown add auxiliary relay 532X. Furthermore, as long as a car isconditioned for upward travel and is not responding to a high callreverse stop it briefly energizes the up add auxiliary relay 531X foreach stop unless the system is operating on its down peak program toopen contacts 582 in line 409. Thus, the car A circuit is completed atlines 410 and 409 through in service relay contacts IS, door controlcontacts D0 which are normally closed, first floor relay contacts 1Fwhich are closed and open when the door is fully closed as long as thecar is not at the first floor, and normally open brake contacts B thatclose as long as the car is in motion, normally closed high call reversecontacts HCR, line 409, up memory relay contacts UL and normally close-ddown peak relay contacts 582. This circuit is closed momentarily orduring the period from the time the doors start to open as the carapproaches a landing and the time that the brake relay is released asthe car stops at the landing.

This circuit is duplicated in lines 413, 416 and 419 for each of thecars so that all of their up stops are added into the up trafiiccounting relay chain. Similar counting of down stops is provided bycircuits including the down memory relay contacts DL, normally closedlight trafiic relay contacts 560 and normally closed up peak programtiming relay contacts 581 in line 420 to add a count into the downtrafiic counting relay chain each time a stop is made. This circuit isonly effective during light trafiic conditions since the light traificrelay 560, shown at line 524 of FIG, V, is energized to open itscontacts at the third level of down traffic demand.

An up subtract relay 533X and a down subtract relay 534X shown in lines404 and 403 respectively are normally energized through normally closedcontacts 533 and 534 of the up and down subtract detector relays 533 and534. These relays are also energized through contacts 531X and 532X ofthe up and down add relays 531X and 532X to prevent a subtraction in thechain of counting relays while an addition is in progress.

The actual drop-out of the relays 533X and 534K is delayed after thedeenergization of their control circuits by means of condensers C1, C2that are connected to the operating coils through resistor R22 or R24 toprovide, for the up subtraction, a delay of four to five seconds, and,for the down subtraction, a delay of two to three seconds; Additionallythe up subtract relay 533X is provided with an additional time delaycircuit comprising resistor R25 and condenser C3 that is connected intothis circuit as long as only one car is in operation as indicated byclosure of one car relay contacts 471, line 407.

FIGURE V A chain of counting relays 536A through 5366 are illustrated inlines 509 to 523 of FIG. V. A similar chain of counting relays 535Athrough 535G, not shown, are employed for counting the up trafficdemands. Since the chains are similar only the one for the down trafficis illustrated. Each of the seven relays 536A through 5366 is of acomposite construction that includes a ratchet controlled set ofcontacts that operate from off to on or from on to oif as the operatingcurrent in the coil of the relay is cut off and thus alternately assumetheir contact opening or contact closing positions. In addition, each ofthese relays includes sets of contacts operated directly by the pawlactuating mechanism each time the coil is energized. Thus, for example,the first down trafiic counting relay 536A has a first set of normallyopen contacts, line 301, that alternately open and close with successivedeenergization of the operating coil. Contacts 536A of the relay 536Ashown in line 302 are operated by the pawl actuating mechanism so as tobreak the detector arm of the bridge circuit each time the operatingcoil 536A is energized. Likewise, contacts 536A in line 504 are closedeach time the operating coil is energized. The remaining contacts, shownin lines 509, 510, 601 and 625, are ratchet operated. With thisunderstanding of the operation of the counting relays 536 the operationof the chain of relays may be traced on the diagram in FIG. V.

Assuming that initially all of the counting relays are in their offposition the first operation of the down add counting relay 532X acts toclose its contacts in line 508 so that current may fiow from theenergized supply lead CS through the now closed contacts 532X, throughadd lead 30, normally closed contacts 53A in line 509 to the operatingcoil 536A. As long as this current flows the contacts 536A in line 302are opened and those in line 504 are closed. Closure of the contacts536A in line 504 energizes reset coils 532R and 534R of the down add anddown subtract detector relays to return these relays to their normalcondition. Returning the down add detector relay 532 to its normalposition opens its contacts in line 421 to deenergize the down addauxiliary relay 532X thereby breaking the circuit in line 508 to the536A operating coil. This coil thereupon releases and the pawl advancesthe ratchet mechanism to the next position thereby closing contacts536A, line 301, and 536A, in line 510, and also opening the contacts536A in line 509. Closure of these contacts in line 301 introduces theresistor R1 into the balancing arm of the down trafiic sensing bridgewhile closure of contacts 536A, in line 510 in the series at the leftside of the diagram, prepares a circuit for the operating coil of thesecond counting relay 536B at the same time that it prepares asubtracting circuit 31 through the normally open contacts 536A shownnear the center of the diagram. Opening of the normally closed contacts536A in line 509 opens the add operating circuit to the counting relay536A.

With the contacts 532X, line 508, open and the normally closed contacts536A, line 509, also open current flows through resistors R36, R37 andcoil 536A to energize a low current indicator lamp 32 to indicate that afirst unit or first level of down traffic is in effect. If the insertionof resistor R1 in the down trafiic measuring bridge circuit isinsufficient to balance the bridge the down add detector relay 532 againcloses its contacts to energize the down add auxiliary relay 532X whichcom pletes a circuit from the lead CS through the now closed contacts536A in lead 30, and normally closed contacts 536B, line 511, to theoperating coil of the second counting relay 5368. This relay immediatelycocks its ratchet mechanism and at the same time opens its contacts53613 in line 303 to open the detector circuit of the bridge at the sametime that it closes its contacts 53513 in line 505 to energize the resetcoils 532R and 534R of the detector relays. As the detector relay 532 isreset it deenergizes the auxiliary relay to open its contacts 532X, line508, and thus deenergize the now energized coil 536B. Its ratchet thencloses its normally open contacts 5353, lines 302 and 512, at the sametime that it opens its normally closed contacts in line 511 to break thecircuit to its coil 536B and, at the same time, in line 512 break thesubtract circuit ,34, leading up the center of the diagram, to the coil536A of the first counting relay 536A. This adding operation ofadditional relays 536 is repeated until the bridge shown in the top ofFIG. III is balanced. This may result in the operation of several or allof the counting relays 536A through 5366.

As the calls are answered the down hall call relays are deenergized andthus remove resistors RX from the measuring arm of the bridge. Also asloaded cars arrive at the first floor resistors RY are disconnected fromthe measuring arm of the bridge. If an equivalent number of new downhall calls are not registered the bridge is then unbalanced in theopposite direction from the first unbalance. The bridge is rebalanced bya subtraction operation in the chain of counting relays to remove anequivalent number of resistors from the balancing arm of the bridge.This substracting operation begins with energization of the polarizeddown subtract detector relay 534, line 310, which, when actuated, opensits contacts 534 in line 403 to break the circuit to the down subtractauxiliary relay 534X. When this relay drops out following a time delayof two to three seconds provided by condenser Cl it closes its normallyclosed contacts 534X in line 522 to complete a subtracting circuit fromthe energized line CS through a lead in line 522 including the nowclosed contacts 534X and thence up through a subtracting lead 31 in thecenter of the diagram including the normally closed contacts 536G, 536F,etc, of any non-operated or off counting relays and thence through thenormally open but now closed contacts 536 to the right of lead 31 of thehighest order counting relay that is on the on condition. Thus, assumingthat four levels of down traffic have open registered to balance thebridge circuit resulting in operation of relays 536A through 536D to theon conditions the subtracting pulse is fed through the normally closedcontact 536G, 536F and 536E, in lines 522, 520 and 518 and thencethrough the normally open contacts 536D to the operating coil 536D. Thisprovides a second energization of the operating coil of this relay sothat it cocks its ratchet mechanism and at the same time opens itscontacts 536D in the detector diagonal of the bridge circuit at the sametime that it closes its contacts similar to those in line 565 toenergize the reset coils 532, 534. The reset coil 534 immediately resetsthe down detector subtract relay 534 so that it again energizes itsauxiliary relay 534X to open the substract circuit at line 522.

As the counting relay 536D is deenergized by the opening of the contacts534X in line 522 its pawl and ratchet moves its contacts to thepositions shown thereby taking the resistor R4 out of the balancing armof the bridge as well as preparing the subtracting circuit to the nextlower .trafiic level counting relay 536C. This action may be repeatedwith the counting relays 536C, 536B and 536A to again bring the bridgeinto a balanced condition.

Since the operating coils of the counting relays 536A through 535G areheavy duty coils on account of the ratchet mechanism, rectifiers 33 and34 are connected from the add lead 30 and the subtract lead 31,energized through contacts 532X and 534X, to the grounded lead 60 toabsorb the inductive voltage surge as these contacts open to deenergizethe operating coils of the relays.

A light traflic relay 560 shown in line 524 is arranged to be energizedwhen the counting relay chain reaches a third level as indicated byclosure of contacts 5360, line 524. This relay then seals itself inthrough counting chain contacts 536B of a second level relay and its owncontacts 560 so that the relay remains energized until the countingchain returns to the condition with only one counting relay in its onposition. The dropout of the low trafiic relay 560 is delayed by atiming condenser C6 connected in parallel with its operating coil. Aresistor R45 is inserted in series with the condenser to limit the peakcharging current and thus protect the contacts 536C from the initialsurge of current flowing to the condenser when the contacts make.

The two chains of counting relays, the series 535A through G and theseries 536A through G, provide, according to the number of countingrelays energized in each series, a quantitative indication of thetrafiic demand then existing in the system. This quantitative indicationof the traffic demand in the up and down directions may be employed toinstitute specific programs of operation or control a number offunctions in the supervisory control of the elevator system, Forexample, an increase in traffic level may call for the starting of idlemotor generator sets and elevators to meet an increased demand. Thequantitative traffic demand indication may also be employed to regulateor adjust the dispatching timing intervals at each of the terminals ofthe system so as to keep the cars properly spaced to give the bestservice.

Of the many types of programs that may be employed in the operation ofan automatic elevator system the up peak program and the down peakprogram are two that are employed in practically any installation. In anofiice building, for example, the up peak program occurs at thebeginning of the business day when the building occupants are coming towork. A similar situation occurs at the end of the lunch period whenthose tenants who have left the building for lunch are returning totheir offices. Down peak trafiic patterns occur at the beginning of thelunch hour in some types of buildings and again at the close of thebusiness day when the ofiices are closing and the occupants are leavingthe building. The quantitative indication of traffic demand afiorded bythe bridge circuits responsive to various indications of traflic may beemployed in the circuits shown in FIG. V to set. up the up peak or downpeak programs and hold such programs in effect until the trafficconditions calling for such programs have subsided.

FIGURE VI In the circuits shown in FIG. VI a timer supply lead 35 isenergized from the control circuit power lead CS as long as three orfour cars are in operation as indicated by closure of three car or fourcar relays 473 or 474 having contacts shown at lines 602 and 604. Thislead 35 provides direct current power for the circuit of the up peaktimer relay 581 shown in line 603 and up peak cancel timer 583 shown inline 610 and, through normally closed contacts of a no-call relay 430,to down peak timer 582 shown in line 617 as well as a down peak canceltimer 584 shown in line 622. The up peak cancel timer 583 has normallyclosed contacts 583 in line 604 which permit current to flow from thelead 35 through an operating coil 581 of the up peak timer and thenthrough a grid controlled glow discharge tube 36 whenever the potentialon its grid 37 exceeds a certain critical positive potential. The uppeak timer 581 may also be energized immediately through seriesconnected normally closed contacts 9 536A of the first level downtraific counting relay 536A and normally open contacts 5356 of theseventh level up trafiic counting relay 535G shown in line 601 in theevent there is no down trafiic demand and a maximum amount of up trafficdemand. 1

The grid controlled tube 36 is fired to energize the up peak timer relay581 after time delays depending upon the level of up traffic demandcoupled with a lesser level of down traflic demand. Thus, if there isless than a fourth level of down trafiic demand such that contacts 536Dare closed at line 607 and there is at the same time at least a fourthlevel up traffic demand as indicated by closure of contacts 535D voltageis applied through a voltage divider comprising resistors R62 and R63.

This voltage applied across the resistor R59 and condenser C9 chargesthe condenser to the firing voltage of the tube 36 in approximately tenseconds. This timing may be varied according to the demands of aparticular installation. When this relay is energized by current flowthrough the tube 36 it closes its contacts in line 602 to provide aby-pass circuit through resistor R57 around the tube 36 thus loweringthe plate voltage below the ex tinction potential to deionize the tube.It also closes its contacts 581 in line 607 to discharge the timingcondenser C9 through resistor R61 thereby preparing the circuit for afull timing interval the next time the circuit is completed for timing.

If during this timing operation controlled by resistors R62 and R63 thedown traflic subsides to release counting relays 536C and the uptrai'fic demand increases such that the next trafiic counting relays53513 is actuated to its on position it closes its contacts 535E, line606 to shunt resistor R58 around resistor R62 thus raising the voltageon the lead 38 to accelerate the timing operation. Likewise, if the uptraffic demand increases to the point where the sixth traffic levelrelay 535F is actuated to its on position and the down traflic subsidesthe maximum voltage is applied to the lead 38 resulting in a minimumtime interval for the timing out of the up peak timer and energizing itsrelay 581.

In ordinary operation the up peak timer is deenergized after the up peaktrafiic subsides. In some arrangements certain operating features arecommon to both up peak and down peak operation. In such cases it isdesirable to maintain the up peak relay energized during down peakoperation. If the up trafiic subsides in the absence of down tratlic theup peak cancel timer acts to deenergize the up peak timer 581. Thecircuit for the up peak cancel timer 583, is prepared when the up peaktimer 581 closes its contacts 581, line 610. This applies platepotential to a second grid controlled cold cathode gas discharge tube 39which fires to energize the relay 583 whenever the potential on its grid40 exceeds a critical positive voltage. As long as at least a fourthlevel of up traffic demand is registered by the up trafiic countingrelays 535, contacts 535A, 5358 and 535C in lines 613, 612 and 611 areopen so that the grid 40 of the tube is held at ground potential throughresistors R69, for limiting grid current, R68 for controlling thecharging current to condenser C10, and R71 serving as part of a voltagedivider that includes resistors R65, 66 and 67 for determining thetiming interval for this circuit.

-As the up traffic level subsides and the bridge circuit follows thedecrease the counting relay 535C is returned to its off condition. Thisrelay, by closing its normally closed contacts 535C in line 611completes a circuit through resistor R65 to a junction lead 41 therebyapplying sufiicient voltage to lead 41 to allow the condenser C to becharged slowly and after an appreciable time delay of approximately twominutes energize the up peak cancel timer 583. This relay then closesits contacts in line 609 to by-pass the tube 39 and thus deionize it andat the same time opens its contacts in line 604 to break the circuit tothe up peak timer 581. The up peak timer then drops out unless there isdown traffic to hold light down traflic relay 560 contacts closed inline 602 and no motor generator set is being shutdown to open normallyclosed contacts 517. In the event the up trafiic demand subsides rapidlythe up traffic counting bridge circuit subtracts the next countingrelays from the up trafiic counting chain of relays 535. These relays5358 and 535A then close their contacts to shunt resistors R66 and R67in parallel with resistor R to accelerate the timing out of the up peakcancel timer 583.

Similar circuits for the down peak timer 582 and down peak cancel timer584 are prepared for operation as long as there is at least one hallcall so that normally closed contacts 430 of a no hall call relay areclosed at line 615 to connect the lead 35 to a continuing lead 42. Thesecontacts thus insure that the down peak timers cannot be energizedunless there is at least one down hall call.

A down peak timer 582 to institute a program suitable for down peaktraffic is prepared for operation as long as the down peak cancel timer584 is deenergized to close its contacts 584 in line 617. This down peaktimer 582 can be energized immediately in the event there is a maximumamount of down trafiic demand and no up tralfic demand so that uptraific counting relay 535A is deenergized while down counting tratficrelay 536G is energized and thus closes the circuit in line 615. The

down peak timer relay 582 may be energized after time delays by circuitsin lines 618 to 621 that act to apply sufficient potential to a lead 43so that it may, through resistor R74, charge condenser C11 to apotential such that a grid 44 of a grid control gas discharge tube 46may fire and thus energize the relay. If the down tratfic demand reachesthe fourth level so that the fourth counting relay 536D is moved to itson condition it closes its contacts in line 620 to energize the lead 43through resistor R77. The current flowing through this resistor alsoflows through resistor R78, the two resistors forming a voltage dividersuch that the potential of lead 43 is just suificient to charge thecondenser C11 above the break down or firing potential of the tube 46.Time delay in this case is a maximum and may be in the order of tenseconds. If the down trafiic demand increases to a level such that thefifth down traffic counting relay 536E is energized and the up tratfichas subsided to a point where the up counting relay 535C has beenactuated to its off position the timing of the down peak timer may beaccelerated by current flowing through resistor R75 in parallel with R77thus raising the potential on the lead 43 and accelerating the chargingof the timing condenser C11. A still shorter timing interval occurs ifthe down traffic counting relay 536F is energized and the up tratficcounting relay 535B is in its otf position. This indicates a largeunbalance in trafiic demands in favor of down traflic thus calling for arelatively quick changing of the system to a down peak program.

Once the down peak timer relay 582 is energized it closes its contactsin line 616 to complete a by-pass circuit around the tube 46 and at thesame time closes its contacts in line 620 to discharge the timingcondenser C11. This relay then remains energized through its sealingcircuit until either the down peak cancel timer 584 times out to openits contacts 584 in line 617 or there is a momentary or continuedinterval during which there are no hall calls such that the relay 430 isenergized or there are less than three cars in operation as indicated bythe opening of relay contacts 473 and 474 to deenergize lead 35.

The down peak cancel timer 584, which was prepared for operation whenthe down peak timer 582 was energized to close its contacts in line 622,is energized following a time interval whichvaries according to theactual down trafiic demand. Thus, if the down traffic subsides to alevel where the third level counting relay 536C is moved to its 0175condition current flows through resistors R79 and R84, acting as avoltage divider, to

apply a potential to lead 47 sufficiently positive so that the condenserC12 may, in a time interval of approximately thirty seconds, charge to apotential sufficient to cause break down of the glow discharge tube 43to energize the relay 584. The timing out of the down peak cancel timer584 may be accelerated if the down traflic demands subside to the pointwhere the second or in some cases the first down traffic counting relays536B and 536A are moved to their off condition. As these relays move totheir off condition a resistor R80 is first connected in shunt withresistor R79 to raise the potential on the lead 47 thus accelerate thecharging of the condenser C12. Likewise, when the counting relay 1536Ais moved to its off condition it closes its contacts 536A in line 625 toapply a maximum potential to lead 47 and thus provide a minimum timedelay. When this cancel relay 584 is energized it opens its contacts &4in line 617 to deenergize the down peak timer 582.. This relay thenopens its contacts in line 622 to deenergize the relay 584 and at thesame time close its contacts in line 625 to discharge the condenser C12.

The up peak and down peak timer relays 581 and 582 respectively may bearranged to set up appropriate circuits for the supervisory control ofthe elevator system such as instituting high call reverse, changingdispatching time intervals at the terminals or eliminating suchintervals, or adding an additional motor generator set and car toservice, or for initiating other changes in the supervisory control soas to best meet the trafiic pattern then existing in the system.

The just described operation of up peak and down peak program timers areexamples of supervisory control elements that may advantageously employquantitative information of traffic demands and adjust the program ofoperation accordingly.

The trafiic measuring bridge circuits have the advantage of continuouslymonitoring the trafiic demand and may, therefore, quickly call foradjustments in the operating program to meet the demands.

Since in this type of system it is always preferable to have a slightexcess of service available the bridge detector and counting relaysystems are arranged to be instantly responsive to bridge unbalancesindicating increases in trafiic demand. For the same reason the subtractrelays are provided with time delay characteristics to delay for atleast a few seconds any subtract operations. This time delay isparticularly effective during up trafiic patterns when the cars oftenare required to make many stops while discharging a load of passengers.Since an up add count is registered for each stop regardless of balancein the up trafiic bridge the bridge becomes unbalanced and initiatessubtract operations. By delaying the subtract operations the countingrelays remember the stops and thus reflect a more accurate indication ofthe up traffic demand.

During light down traffic, stops are also counted so that the downtraflic counting relays may indicate a slightly heavier traffic thanactually exists. This stop counting thus has the effect of biasing thecontrol system toward the heavier traffic programs.

The measurement of down traffic is based primarily on the number ofunanswered down hall calls. However, to minimize hunting and unnecessarychanges of program, the loads in the cars are also included in themeasurement. A twenty percent load is preferably made equivalent to onehall call. Thus, in an average system, if two or three down passengersenter the car a resistor RY is substituted for the resistor RX, whichwas taken from the bridge circuit as the hall call was answered, and thebridge balance is not changed.

In the up trafiic bridge the measurement depends primarily on the loadsin the cars. This is supplemented by the existence of up calls at theterminal and a car call registered in the car. Since each twenty percentof load counts as one unit, and a car call counts as a half unit or oneunit, depending on the system, a fully loaded car leaving the terminaladvances the bridge and counting relays to the fourth level. Other carsmay still be partly loaded so it is thus possible to register with twocars a peak up traffic demand. Such a situation existing for a fewseconds would throw the system into up peak operation.

The bridge circuits thus measure the traffic demands in terms of thenumber of unanswered hall calls and the amount of load in the cars. Thecounting chains of relays for rebalancing the bridge circuits are, undercertain conditions, further biased toward heavy traffic indications bycounting the number of stops performed by the cars.

These circuits thus provide a continuous indication of traffic level andprovide means for instituting appropriate programs of operation to meetthe trafi'ic patterns as they occur.

Various modifications may be made in the various circuits described forcontrolling the operation of a bank of elevators according to theobserved traffic demand and instituting programs of operation inaccordance with such demand without departing from the spirit and scopeof the invention.

Having described the invention, I claim:

1. In an elevator system, in combination, a plurality of elevator carsarranged to serve a plurality of floors, means for operating said carsin response to demands for service, means for measuring traflicdemand'by measuring the number of unanswered down hall calls, the loadsin the cars during up trips, and the loads in the cars during downtrips, and means for correlating such measurements to indicate heavy uptraffic and heavy down traffic and means for instituting up peak anddown peak programs of operation to serve the traffic pattern thenindicated by such measurement correlation.

2. In an elevator system, in combination, a plurality of elevator carsarranged to serve a plurality of floors, means for operating said carsin response to demands for service, means for measuring the number ofunanswered down hall calls and the loads in down traveling cars, andmeans for instituting a down peak program of operation to serve a downtraffic when such measurement attains a certain level.

3. In an elevator system, in combination, a plurality of elevator carsarranged to serve a plurality of floors, means for operating said carsin response to demands for service, means for measuring such demands forservice that includes a bridge circuit one arm of which compriseselements representing unanswered hall calls and a balancing arm of whichcomprises balancing elements representing levels of traffic demand,means for balancing the bridge by altering the effective number ofbalancing elements included in such bridge circuit, and means responsiveto the number of said balancing elements included in the bridge formodifying the operation of said elevators.

4. In an elevator system, in combination, a plurality of elevator carsarranged to serve a plurality of floors, means for operating said carsin response to demands for service, means for measuring such demands forservice that includes a bridge circuit one arm of which comprises aresistor for each unanswered hall call and each increment of load indown traveling cars, and a balancing arm which comprises balancingresistors corresponding in number to traffic level being indicated,means for varying the number of balancing resistors included in thecircuit to balance said bridge circuit, and means responsive to thenumber of balancing resistors in said bridge circuit adapted to modifythe operating program of the elevator system.

5. In an elevator system, in combination, a plurality of elevator carsarranged to serve a plurality of floors, means for operating said carsin response to demands for service, means for registering such demandsfor service, means for measuring such demands for service that includesa bridge circuit one arm of which comprises a plurality of elements onefor each unanswered hall call and one for each increment of load in downtraveling cars and a balancing arm of which comprises a plurality ofbalancing elements, a detector sensitive to bridge unbalance, a seriesof counting means that are successively energized and deenergized inresponse to said detector, said counting means serving to vary thenumber of balancing elements included in the bridge circuit, and meansresponsive to the counting means for modifying the operating program ofsaid elevators.

6.- In an elevator system, in combination, a plurality of elevator carsarranged to serve a plurality of floors, means for operating said carsin response to demands for service, means for registering demands forservice, means for measuring the demand for service comprising a bridgecircuit one arm of which comprises an element for each increment of loadin up traveling cars and a balancing arm of which comprises a pluralityof balancing elements, a chain of traflic counting means adapted to varythe number of balancing elements included in said bridge arm forbalancing said bridge, a detector for said bridge adapted tosuccessively energize said counting means in response to unbalance inthe bridge circuit to vary the number of balancing elements in thecircuit, and means responsive to said counting means for modifying theprogram of operation of said elevators.

7. In an elevator system, in combination, a plurality of elevator carsarranged to serve a plurality of floors, means for operating said carsin response todemands for service, means for registering demands forservice, means for measuring the demand for service comprising a bridgecircuit one arm of which comprises an element for each increment of loadin up traveling cars and a balancing arm of which comprises a pluralityof balancing elements, a chain of counting means adapted to vary thenumber of balancing elements included in the bridge circuit, a detectorfor the bridge circuit adapted to energize the counting means in adirection to balance the bridge circuit, means responsive to up stops ofthe elevators for energizing the counting means to vary the numberbalancing elements in the bridge circuit, and means responsive to thecounting means for varying the program of operationof the elevatorsystem.

8. In an elevator system, in combination, a plurality of elevator carsarranged to serve a plurality of floors, means for operating said carsin response to demands for service, means for registering demands forservice, means for measuring the demand for service comprising a bridgecircuit one arm of which comprises a resistor for each unanswered hallcall and certain increments of load in down traveling cars and abalancing arm of which comprises a variable number of resistors,counting means arranged to vary the number of resistors in saidbalancing arm, a detector responsive to an unbalance in said bridgecircuit in a first direction adapted to immediately add counts in saidcounting means and responsive to unbalance in a reverse direction forsubtracting counts at timed intervals, and means responsive to thecounting means for modifying the program of operation of the system ofelevators.

9. In an elevator system, in combination, a plurality of elevator carsarranged to serve a plurality of floors, means for operating said carsin response to demands for service, means for registering demands forservice, means for measuring the demand for service comprising a bridgecircuit one arm of which comprises an element for each demand forservice and for each of certain increments of load in the cars, and abalancing arm of which comprises a plurality of balancing elements,means for balancing the bridge including a detector and counting meansfor immediately successively adding said balancing elements into saidbalancing arm to correct an unbalance in a first direction and forsuccessively subtracting balancing elements at timed intervals tocorrect an unbalance in a reverse direction, and means responsive tosaid counting means for modifying the pro-gram of operation to meet themeasured traflic demand.

10. In an elevator system, in combination, a plurality of elevator carsarranged to serve a plurality of floors, means for operating said carsin response to demands for service, means for measuring such demands forservice that includes a bridge circuit one arm of which compriseseiements representing car loading and unanswered hall calls and one armof which comprises balancing elements representing levels of traflicdemand, means for balancing the bridge by altering the effective numberof balancing elements included in the bridge circuit, and timing meanshaving time delays that vary with the number of balancing elements thenincluded in the bridge circuit for instituting and canceling certainprograms of operation in accordance with the traffic demands representedby the balancing elements included in the bridge circuit.

11. In an elevator system, in combination, a plurality of elevator carsarranged to serve a plurality of floors, means for operating said carsin response to demands for service, means for measuring such demands forservice that includes a first bridge circuit having a first armcomprising elements representing unanswered hall calls and increments ofload in down traveling cars and a second arm comprising balancingelements representing levels of traffic demand, means for balancing thebridge by altering the effective nurnber of balancing elements includedin the circuit, a second bridge circuit having a first arm comprisingelements representing loads in up traveling cars and a second armcomprising balancing ele. ments representing levels of traflic demand,means for balancing the second bridge by altering the number ofbalancing elements in the second arm, circuits for instituting andcanceling a program of operation, said circuits being connected to thebalancing means of said bridge circuits and responsive to the level oftraflic demand indicated in each bridge circuit.

12. An elevator system according to claim 11 in which the circuits forinstituting and canceling a program of operation include timing meansthe timing intervals of which vary according to the level of tratlicdemand indicated by the bridge circuits.

13. An elevator system according to claim 11 in which the circuits forcanceling a program of operation responds to a lower level of tratficdemand than the circuit for instituting such program of operation.

14. An elevator system according to claim 11 in which the circuit forinstituting a program of operation has a time delay that varies with thelevel of trafiic demand and is short when compared to the time delay ofa circuit for canceling the program of operation.

15. In an elevator system, in combination, a plurality of elevator carsarranged to serve a plurality of floors, means for operating said carsin response to demands for service, means for quantitatively measuringsuch demands for service in each of two directions of travel, meansresponsive to the measuring means for instituting a peak program ofoperation in response to a predetermined excess of demand in onedirection over the demand in the other direction, said instituting meansbeing instantly responsive to a certain excess in demand and beingresponsive to a lesser excess of demand maintained over a time interval.

16. In an elevator system, in combination, a plurality of elevator carsarranged to serve a plurality of floors, means for operating said carsin response to demands for service, means for quantitatively measuringsuch demands for service in each of two directions of travel, meansresponsive to the measuring means for instituting a peak program ofoperation in response to a predetermined excess of demand in onedirection, said instituting means being responsive to certain levels ofexcess of demand maintained for certain intervals of time, and means forcanceling said peak programs in response to a continued reduction insuch excess of demand.

17. In an elevator system comprising a plurality of cars serving aplurality of landings, means for measuring traffic conditions in saidsystem for a given direction of travel, means for altering the operatingpattern of said system to provide a preponderance of service in saidgiven direction of travel, a timer for actuating said pattern alteringmeans to provide for preponderant service in said given direction uponexpiration of an interval of at least a given level of trafficconditions for said given direction, and means to vary said intervalinversely with said traflic condition level.

18. In an elevator system comprising a plurality of cars serving aplurality of landings, means for measuring trafiic conditions in saidsystem for a given direction of travel, means for altering the operatingpattern of said system to provide a preponderance of service in saidgiven direction of travel, a timer for actuating said pattern alteringmeans to provide for preponderant service in said given direction uponexpiration of an interval of at least a predetermined level of trafficcondition for said given direction, means to vary said intervalinversely with said traflic condition level, and means to actuate saidpattern altering means to provide for preponderant service in said givendirection upon the sensing of a second predetermined level of saidtrafiic condition for said given direction.

19. In an elevator system comprising a plurality of cars serving aplurality of landings, means for measuring traffic conditions in saidsystem for a given direction of travel, means for measuring traflicconditions in said system for a direction of travel opposite said givendirection, means for altering the operating pattern of said system toprovide a preponderance of service in said given direction of travel, atimer for actuating said pattern altering means for providing apreponderance of service in said given direction upon sensing at least apredetermined preponderance of the traffic condition level in said givendirection over that condition in said opposite direction for a giveninterval, and means to vary said interval init; versely with the degreeof preponderance of traffic conditions in said given direction.

20. In an elevator system comprising a plurality of cars serving aplurality of landings, means for measuring traffic conditions in saidsystem for a given direction of travel, means for measuring trafiicconditions in said sysem for a direction of travel opposite said givendirection, means for altering the operating pattern of said system toprovide a preponderance of service in said given direction of travel,and a timer for actuating said pattern altering means for providing apreponderance of service in said given direction upon sensing at least apredetermined preponderance of the trafiic condition level in said givendirection over that condition in said opposite diection for a giveninterval.

21. A combination according to claim 20 including means for actuatingsaid pattern altering means for providing a preponderance of service insaid given direction upon sensing of a given second level ofpreponderance of tratfic conditions in said given direction over traflicconditions in said opposite direction.

22. In an elevator system comprising a plurality of cars serving aplurality of landings, means for establishing an operating pattern inthe system for providing a preponderance of service in a givendirection, means for sensing the level of traffic conditions in saidsystem for said given direction, a timer for rendering said patternestablishing means ineffective a predetermined interval following thedecline of the level of traflic conditions for said given directionbelow a predetermined level, and means to reduce said interval as afunction of the reduction of the level of traffic conditions for saidgiven direction.

References Cited by the Examiner UNITED STATES PATENTS 2,581,245 l/l952Eames 187-29 2,827,980 3/1958 Suzzo et al. 18729 ORIS L. RADER, PrimaryExaminer.

MILTON O. HIRSHFIELD, Examiner.

G. G. JENSEN, B. DOBECK, Assistant Examiners.

1. IN AN ELEVATOR SYSTEM, IN COMBINATION, A PLURALITY OF ELEVATOR CARSARRANGED TO SERVE A PLURALITY OF FLOORS, MEANS FOR OPERATING SAID CARSIN RESPONSE TO DEMANDS FOR SERVICE, MEANS FOR MEASURING TRAFFIC DEMANDBY MEASURING THE NUMBER OF UNANSWERED DOWN HALL CALLS, THE LOADS IN THECARS DURING UP TRIPS, AND THE LOADS IN THE CARS DURING DOWN TRIPS, ANDMEANS FOR CORRELATING SUCH MEASUREMENTS TO INDICATE HEAVY UP TRAFFIC ANDHEAVY DOWN TRAFFIC AND MEANS FOR INSTITUTING UP PEAK AND DOWN PEAKPROGRAMS OF OPERATION TO SERVE THE TRAFFIC PATTERN THEN INDICATED BYSUCH MEASUREMENT CORRELATION.